Method of and machine for making circular fluorescent lamps



Sept. 23, 1952 H. c. sNow ETAL METHOD ANDMACHINEl FOR MAKING CIRCULAR FLUOREISCENT LAMPS Filed March 25, 1949V 8 Sheets-ShedI l ard YW Q55 ts:

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W ET AL METHOD OF AND MACHINE FOR MAKING CIRCULAR FLUORESCENT LAMPS Filed March 25, 1949 8 Sheets-Sheet 2 MMV Sept.. 23, 1952 H. C. SNO-W ET AL METHOD OF' AND MACHINE FOR MAKING CIRCULAR FLUORESCENT LAMPS 8 Sheets-Sheet 5 Filed March 25, 1949 flle 0 ww e5 W5 im Sept. 23, 1952 H. c. sNow ET AL METHOD OF AND MACHINE FOR MAKING CIRCULAR FLUORESCENT LAMPS 8 Sheets-Sheet 4 Filed March 25, 1949 .MNM 1| MW I O www n www www@ Sept. 23, 1952 2,611,216

METHOD oF AND MACHINE FOR MAKING CIRCULAR FLUORESCENI LAMPS H. C. SNOW ET AL s shees-fsheet 5 Filed March 25, 1949 v Inv/venan; 170mm wzd a'ere septzs, 1952 'HCQS'NOW mL 2,611,216

METHOD OF' ND MACHINE FOR MAKING CIROUIAR `F'LUOREISCENTLAMPS Filed March 25, 1949 y 8 sheets-sheet e D A Y T m 8 x1 '1 m. Q

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Spt. 23, 1952 H. C. SNOW ET AL METHOD OF` AND MACHINE FOR MAXI-NG CIRCULAR FLUORESCENT LAMPS 8 Sheets-Sheet 7 Filed March 25, 1949 Sept. 23, 1952 Il-l. c. sNow ET AL 2,611,215

METHOD OF AND MACHINE FOR MAKING CIRCULAR FLUORESCENT LAMPS Filed March 25, 1949 A 8 Sheets-Sheet 8 RQQ Qs Nw Q\` Patented Sept. 23, 1952 5 vfumi15u`v strates PA*'rgitl'iv Y 2,611,216 Y Maanen or ANDMACHINE roni'l1/iarultr-d,` Y

Cineman nLuoREscEN'r Larmes l A y Howard C. Snow, Swampscott, EverettilaKelley,k c v Melrose, and Samuel S. Saywardr;Danvers,V` z

.Massa assigncrs to Consolidated Electric Lamp j Company, Lynn, Mass., a corporation of Massachusetts 't Application March 25 g 19 claims. (co1. Visa-*1) This invention relates cent-lamps, theprincipal objects being to provide a method of converting partial-ly manufactured straight-I glass tubes of the type commonly 'em- 'ploy'ed-in themanufacture ofV straight uorescent lamps tinto substantially circular lamps of uniforml curvature and cross-section; and to provide a machine'` which will bend partially manufactured-straight tubular lamps or bulbsplaced therein into substantially circular form; G therobjects areftoprovide a 'machine in which straightV lamp tubes maybe loaded on at one point'andstepped along at suitable intervals to instrumentalities which will convertl the straightl tubesinto circular form, the foregoing being accomplished rapidly, efciently and with greater uniformity than could be possibly attained by priormethods rorlrnachines.A Still other objects are to provide amachinewhich is automatic or semi-automatic AinV operation, which is simple in construction and is substantiallyfoolproof. l,

In accordance with the foregoing objects a partially manufactured lamp consisting of a straight, hollow glass tube, preferably coated; on `'the inside, having' sealed in mountsA at its' ends, the mount at one Vend having anexhaustv tube attached theretov and having vclamp 'caps secured to its ends; is held suspended at 'the exhaust tube end inA a substantially vertical positionY while in a softened condition yand its lower end is then `gripped andv rolled upwardly about a center which4 lies along a line parallel to its vertical axis and distant therefrom by'an amount equal to the radius of the circle to be formed.

vIn accordance with one aspect ofthe method herein f illustrated, the partiallyj manufactured lamp tube is differentially plasticizedfso-thatoney side -is softerthan the other and-is then bent to substantiallycircular form so that thesofter side willbe at'the inside'of the completed lamp.v

In practice the lamp -tubefis exposed asia` Whole to controlled 4heat `toplasticize itsv walls and then one side is cooled somewhat to vlower its plasticity'particularly along the portion of the tube which will constitute substantially the lower outer half of the rolled-up' tube as supported during bending and prior to final setting. Cooling is effectedv by playing currents of gas or air over the surfaces of the tube. `It is also contemplated that air or a rare gas may be introduced to the interior of the lamp at progres-f sively increasing pressures throughout the rolling operation to prevent wall collapse..

The machine includes to a method of and. machine for making circular or curved iuoresa series vof supports- ,1949, SeriallNo. 83,356-

which travelinagenerally closed pathfso as .to be lmoved at suitable intervals through a series of ystations in succession, andat one` station to hold a partiallyV manufactured lamp hereinafter to be referred toas the lamp suspended i bygits upper end within the confines of an oven whielfiheats ,the lampuntil it. softens, whereupon; it

' stretches somewhat-under lits'owngwigllt, The

oven is sectionalandelongation offthellamp ejfects actuation of means whichppens the oyen by separating one section from the gothelbbrings gripper means into.I operationgin Y,1a/manner 1 to grip the lower end-and then -effectsmovement ofthe gripper: meansv upwardly. relative? to the lamp to roll the lamp upwardly-about a circular mold member constituting apart thereof.

of air or other gaseous, medium on the side of the lampwhich will constitute the outside whenV rolled up near its upper end when the oven is open,.thereby to coolthis portion of the wall' just before itis rolled up.

.The moldfmember'is in the form of a pair of separabledisks which together-have in their A peripheral surface a shallow. semi-circular groove which is the lconverse of thecurved surface of the straight lamp; The gripper means comprises a pair of cooperating gripper elements.v

onev carried by each of .the'disks,` the latter vwhen brought, together to form the groove-effecting engagement of. the. gripper yelements with the lower endl At thetmomentA that-upward movement of the mold member isstarted, air or rare gas under pressure Vis introduced tothe interior of the lamp and is uniformly increased inpressure throughout'the rolling operation. VAt the upper limitl of its. movement 'the mold member dwells for a predetermined length offtimer tov permit theV rolled up lamp, to set, then releases the lamp, and finally descends to its initial position. At this point the vsupport'turns throughv one4 step' so as to `carrytherolled up lamp to the next station vof the machine and simultaneously totbring another straight lamp into-the ovenor oyens and tov close the latter. succeeding station there is means fortrocking the supporty to'rotat'eN the circular. lamp through an angle which willtip-:the plane of theupper end* from a substantiallylhorizontalposition to a nearly: vertical position. to bring. the exhaust tube-Lto a1nearly vertical positionr inkreadiness to bel connectedto'aniexhaustrpumpat.

The invention willi now. be described in greater` detail withzreferencefto the accompanying; drawing'snrwhichzb v v Jetsaregarranged next to the oven Vto `play streams.

Fig. 1 is a front elevation of the machine showing the mold member in its initial inoperative position;

Fig. 2 is a fragmentary front elevation of the machine showing the mold member at the top of its vertical travel after having rolled a straight tube into circular form;

Fig. 3 is a plan view of the mold member in-v the inoperative position with the jaws separated;

Fig. 4 is a detail of limit means'for controlling the position of the jaws at the beginning and end of movement of the mold member;

Fig. 5 is a plan view of the machine looking l down at the top of the oven Withr'part of the index head and the operating mechanism omitted;

Fig. 6 is a plan view to larger scale of the ovenopening mechanism;

stantially circular form.

Fig. 7 is a plan view of the indexing head showing the supporting arms, the preheating station, the -bendingstation-and the annealing station Fig. 8 is a horizontal section on a larger scale oftheovem.` Y-

Fig; 9s aplan view of yone' of the supporting Fig-110 isa side view in elevation of Fig. 9;-

11 is afside elevation of the gripper for the top end -of the lamp showing it-tilted to one side to-fperm'it exhausting the.' tube and the details of the controlftrig'ger; n

V41ig-.11"^=shows the head of thel trigger to larger Scale'su'pporting the lower base of the lamp; and 12 is a schematic layoutV of the control cireuitfor the machine'. l

'MAS disclosed herein according to the method aspectY of this invention. a straight v'partially manufacturedfluorescenti lamp tube ST (Fig. 2),1`h`aving"sealedinmounts and metal clamp caps BI and B2 atits opposite end, is softened byheating and then rolled up into substantially circular shape, as shown a't CT (Fig-11)V wherein the ends are brought together to form a nearly complete circle. The distance between the shoulders of ythe rolled-up tube just behind -the @lamp caps is represented by the angle between the doteand-dash lines a-b., :1f-bv extending f rom the geometricjc'enter of the rolled-up tubethrough these shoulders, and this angle is appro'ximately 17 degrees but will vary with lamps of different size. Formation of this circular tube is effected after the tube Vis softened by support-4 ing upperend (Fig. 2). of the tube and then moving the. lower end-.ofthe tube along a line L, whichis cycloidal in shape, whose base is represented by the doti-dash line B, which is the center line of thesuspended'tube'and equal in length,l thereto. andwhich is generated by rolling a circle having aradius R equal to the median 'radiusl of the completed circular tube. along this base. Prior to rolling the tube, a stream of air Cior-l other gaseous medium is played on one wall of the plasticized tube near its upper endV to make vthis side somewhat less plastic sov .that'when-the tube is wrapped about the mold member, as will appear hereinafter, the softer side wall will be next to `the moldand the less plastic sidewill be outside.' .The cooling air may also be played'on the tube at its lower end or even throughout the entire length thereof. The apparatus for `converting the partially manufactured straight lamp'tubes, hereinafter tobe referred' to as lamps, to circular form will nowbe described, and consists generally'of.. an intermittently rotatable support ,or indexing The indexing head I0 is designed to accom- Amodate a plurality of lamp tubes, and, as illustrated in Figs. 5 and 7, comprises a spider I6 having fixed to it and extending radially there- `from eight equallyspaced arms I8` It is to be understood that the index head may be designed nfor example, the machine was made duplex thereby to double production. The spider is xed to the upper end of a vertical shaft 2D, the latter being secured in suitable vbearings provided in a pedestal-like base 22 which supports thesame from the floor. A motor MI (Fig. 12) imparts rotationto the shaft 20 intermittently in accordance with control means and in conjunction with the operation of the other parts of the machine as will appear hereinafter.

Each arm I8 has mounted on it,l as will appear hereinafter, an extension 24 v(Figs. 9 and 10) which has at its outer end clamping means 26 for gripping and holding the upper clamp cap B. As illustrated, the clamping means 26 is comprised of a pair of depending legs 26 and 26h, at the lower ends of which are horizontally arranged cooperating jaws 28 and 28b forming a diamond-shaped opening 28 defined by four quadrilaterally arranged straight ledges 29 for engagement with the metal clamp cap BI of the tube. As illustrated (Figs. 2 and 11a) the metal clamp cap has a conical projection b' and the edges 29 are undercut so as to mate with the sloping wall thereof.

AThe extension 24 is comprised of a solid shaft 30 and a hollow shaft 32 concentrically arranged, and the legs 26'L and 2612 are fixed, respectively, to the shafts 30 and 32. A pair of.upwardly projecting arms 34 and 36 are fastened, respectively, ,to the upper ends of the legs 2ta and 26". The inner end of the hollow shaft 32 is fixed to thevupper end of a post 38, the'latter being se cured at its lower end in a normally yupright position to a horizontal shaft 52- on the radial arm I8. On the inner end of the shaft 30 there is fastened an arm 40. Below this arm there is fixed inthe post38 a studghaving an eye 42 throughk which there is passed a bolt 44, one end of which is fastened to the arm40, and the otherend of which is threaded to receive a nut 46. Between thenut 46 and theeye 42 there is placed on the bolt a compression `spring 48 so that the arm 40 is constantly urged to turn in a. clockwise direction, as seen looking'outwardly along the arm I8, and hence to rotate the leg 26a in a direction to hold the clamping jaw 28* at its lower end close to jaw 28h. `When it is desirable to release a cap held between the jaws 28a and 28h, the operator may grasp the projecting arms 34 and 36 in his hand and squeeze them toward each other, thereby to rotate the arm 26away from 'the arm 2Gb against the action vof the spring 48. Y 1 v As will appear hereinafter, it is desirable to turn the clamping means 25from its initial positionin which' the plane-of the upper cap vis substantially horizontal (Fig. 2) toua`n inclined position (Fig 1l). Accordingly the/,shaft 52 is mounted to turn in a pair of spaced bearings 54; the latter being` xed'to the top sideof the arm I8. The post 38 is normally vheld in its vertical position by-a latch f'pivotally fastened toa post-58 xed to thearmvi-, and has'at one end a lip 68-`adapted to engage anotch 62formed in the face cf the-po`st 38. A tail 64f-carried by th'e'latch is provided by which the latch may be-retracted to withdraw the lip 60 from-the notch 62 and hence tol release the post 38. The post may then be -tipped in a clockwise direction to an inclined position whereit rests against and 1s limited in its movement-by astop screw B6 threadedv into a bracket 88, the latter being fastened -to thearm I3.vv Arod |9-is ,connectedA at itslupper endto the shaft 52 and' at its lower end, which passes through the arm, to a dashpot not shown for cushioning the part 38 as it is tilted-over onto the stop 66.r n I The principal heating means I2, into which a tube ysupported in a vertical position from the arm- I8, as heretofore described, is moved for heating, comprises (Fig. 8) -a substantially cylindrical chamber or oven. made up of two semicylindrical parts 1|) arranged with their open sides-facing each other. `Each semi-cylindrical part has spaced cylindrical walls 'I2 heldin rigid relation to each other by suitable structural mem- 'f bers 'I4 to provide a space 'I6 for insulating purposes.` The upper end of each semi-cylindrical section has a closure plate 18, va part lof which is cut away to form a semi-cylindricalopening 80- ofa size to permit passage' of the clamping which are mounted conventional heating elements Y inthe form of coiled wires. 'To support the halves ofthe oven` for' movement to and from eachother, thatis, to receive a tube as it ap' Y (Figs. 1, 5 and 6), and these rods are situated in'spacedv parallel relation to each other in vertically spaced bearingmembers '94 fastened to the forwardly extending flange of angle members 9S, these latter being bolted to converging walls 91 .of a head casting bolted to the upper end of achannel beam |82. The lower end 'of the channel'beamr-IOZ is'fastened to a base |04 fabricated of C'shaped beams welded together to form a rigid'support for the machine as a whole.y Between the walls of the channel |82 there is secured a horizontal webv IIJI` (Fig. l) in which there is journaled a vertical shaft |08, the lower end of which has attached to it a sprocket I I8. A chain I I2 connects this sprocket to a sprocket I I4 carried by a shaft I I6 which rises from a gear reduction unit I|8 attached to an electric motor M2 fastened to the base of the machine. The oven motor M2 (Fig. 1) provides the power for open--v ing and closing the oven, rand is operated at the 6 proper times in'V the sequence ofA operations,-v as will'appea-r hereinafter.v `The'upper` end of the shaft IUS-has fixedth'e'ieto'a disk |22 (lii'gkv and to thefpper-s'urfacef of this disk thereis fastened by a pivot I24-one end of eachof a pair of links |25 andflza f The opposite ends-:ofthe links are connected, respectively. to apair of arms |30 and |32. these in turn being xed to the lower ends of the vertically spaced rods92. Rotation of the disk-I2'2, accordingly, 'willlimpartmove v ment'totlie arms |30 and `|32 in opposite direc; tions andvhencefrotate therods -92 in opposite' directions to separate the -halves of the vovenorto bring them together.

The heating period will depend upon the'kind; ofI glass, thickness thereof, A andl various other factors and may be shortened to speedup the operation of the machine as a whole,by providing one or more preheating ovens`I2 (-Fig.'-7)`, only one `being's hown'f-herein, situated far enough ahead of the principal oven |2"tocontainfwithin its connes the succeeding tube on the index head so that while one tube is in the oven I2 receiving its final heating, one' or more tubes willbe undergoing f preheating The preheating oven may even be of sufficient length to contain 'aplur'alifty of tubes'. r Thedetail's of the-preheating"ovenA are not described herein since-it'rnay-b'e' of conventionalv design. 1 i herelisalsosituated ahead of the oven |2l a nozzle N '(Figs.' 2and l1) which is supplied with air or other vgas under pressure, the nozzle being situated Vsofas to play a stream of air or' other gaseous medium over one wall of the lamp near one end and on "the'side' which will form thc outside-of the rolled-up lamp. While the'cooling' air may be -'played over the entire length offthe lamp along`1that side, the importanti-partito 1be cooled isthat portion beg-inning at theupper'end and extendingfdownwardly a distancewhich'will behsubstantially commensurate 'with the lower half of the circular lamp, that is, approximately one half of the length of the lamp when-rolled up.'A Thestreamof air, as shown, is delivered Y continuously during operation of the machine :and

impin'ges upon the 'lamp only-when the oven is v tachrnent bei-ng shown at |38."' Fixed tol and extending'vertically' downward from' the trun" nion isa rod |40. the lower end of whichl terminates inthe vicinity of the lower'end-'of the oven'IZ. Near the lower end ofthisfrod` |48 thereis pivotally attached at |42 a trigger mechanismconsistingof an arm7 |44 which has. a downwardly offset Vhorizontal Vportiony |48 conv nected thereto by averticalA portion'f-|46;= A screw |58 Ais fastened to-the free end ofthehorizontal-portion |44 and has on it a-weight |52,- the position of which along the screw may be adjusted by rotating it and may be xed bya nut |54. The horizontal portionl48 extendsl beneath the oven, and yfixed to its free; edfis: a block |56'from the top side of which thereprojectsv upwardly toward the oven and substantially coincident with the'vertic'a-l axis therem of a` post |58 which has at its upper end a head |60'. The headiscomprised'offour radially 7 extending blades spaced 90 degrees apart, each ofy which has` al horizontal portion,` |64 andan upwardly inclined portion |66. The `horizontal portions |64, ares adaptedtoqreceive. the peripheral edge, of the lower clamphcapand toA support the ,same while the inclined portions |66;aot as arpilot togvuideuand center the end of the lamp onto the Vsupporting edges. When the lamp becomes softened to suchvan extent that it stretchesby itsowniweight, it-pushes thehead downwardly and causes the arm to tilt onthe pivot |42 iny aclockwise direction. Normally the weight |52 acts as a counterbalance and holds the arm in a substantiallyhorizontal position, and to limit its initial position there. is provided a stop pin |10 threaded through ar bar |68 fastened to thevpost |40. To limit its downward movement under the influence of the descending lamp, afsecond stop pin |12 isthreaded Vonto the bar |68 at the opposite side of the rod |40. The pivoting movement of the trigger armhactuates a switch st, to, be hereinafter described. It is to be observed that the trigger arm is limited in its downward movement so .that it actuallysupports the lower endlof the lamp after it is depressed. preventingfurther elongation during the` heating period which is continued for approximately four seconds.

The molding or bending means for rolling the lamp into circular form has associated therewith y clamping means |1| (Fig. 1) for engaging the lower clamp cap B2 of the lamp and an annular groove |13 of semi-circular cross-section for receiving the lamp and holding it againstlateral displacement during the vrolling operation. As illustrated (Figs. 3 and 5), .the-mold comprises a pair of disk-likemembers |14 made of some heatffresistant material such as carbon, each of which has one half of theA semicircular surface which forms the annular groove. -The mold members |14 are normally separated, but upon depression of,n thev foregoing head |604 of the trigger mechanism and actuationA of the con-f trol circuit, a motor M3 (Fig. 1) is started which raises them by way of an elevator EA toward the lowerl end of the lamp,` brings the clamping means together about the clamp cap, and then moves them vertically upwardr parallel to the axis of the lamp to effectrolling thereof. To

effect the foregoing movement, each mold memthe former being integral with the forward end n of an arm |84 which -is fastened tothe elevator E, and th'elatter Vwith an arm |86 parallel to the Yarm |84 and attached thereto at its rear end. vMounted on each shaft |18 is a pair of collars |88 and |90, theformer havingassociated therewith a-thrust bearing |92, Be-v tween vthe thrust bearing |92 andthe collar |90 there is situateda spool |94 Amountedwon a pin |96 projectingV from they underside of an arm |98, the armA in turn being pivotally attached at 200 to a bracket 202 bolted to the arm |84.. AtV the rear end of the arm |98 there ispivotally fastened at 204 one end of va link 206, the opposite end of which is pivotally connected to a block 2|0 fastened to a piston rod 2|2 which forms part of a piston and cylinder assembly 2|4vfixed tothe elevator. IntroductionV of compressedair orsome other fluid to the piston and, cylinder assembly 2|4 will effect movement of'I the piston-rod-HZMI'AV in a direction to turn the arms |98 about lthe pivots 200 in opposite directions to shift the shafts |18 to the left or right, as shown in Fig. 3, and hence to move the mold members |14 toward each other. lAsY illustrated, air is delivered to the piston and cylinderssembly 2|4 when the ma.-l chine is set into operation so that prior to and during the upward movement of the mold members to roll the lamp, the piston rod 2|2 is constantly urged in a direction to move the mold members towardeach other. A solenoidcontrolled valve V2 isA provided for admitting air to the cylinder in one direction and to cut offthe vair at the proper time, as will appear hereinafter. A spring 2|| secured between the rear ends of the arms |98 separates the mold members and hence the jaws when the air is cut oif. Movement of the mold lmembers together, however. is restrained prior to engagement with the lamp by links -2|6 (Fig. 3)- pivotally connected at 2|8 to brackets 220 on the arms |84 and midway between their ends bylinks 222 to the arms |98. The links 2|6 are engaged with the outer edges of verticallyl arranged cam bars 226, these cam bars holdingr the links 2|6 spread apart, as indicated, and thus, holding the larms |98 against movement in-adirectionto close the mold members. As thel mold membersrise vto a position opposite the lower end of the lamp, however, the 'links 2|6 ride outA of engagement with the cam bars 226-, thus releasing the arms |98 and allowing the rod 2|2 to impart the motion necessary to bring the mold members together into clamping engagement with the lower clamp cap. To effect vertical movement of the mold members, the elevator E has extending rearwardly therefrom a.V pair of spaced arms 230 which have at their extremities bosses 232 .pierced to ref ceive the ends ofl trunnion pins 234 (Fig. 5) fixed to the opposite, sides of a crosshead 236. The-crosshead 236 hasan opening therethrough and is slidably mounted on a horizontal shaft 238 which passes through the opening and affords a track along which the'l head can slide. TheV shaft 238 is fixed at its ends in posts 240 and 242 (Fig. 1), these in turn being fixed to a base ,plate 244 supported by legs 246 on a portion of the frame 248 and cross-braced to pro'- vide the proper rigidity by members 250. As thus constructed, the crosshead 236 can-slide forwardly and rearwardly along the shaft 238. To Ieffect thevaforesaid movement, a pin 252 (Fig. 3) is fixed between the arms 230 and on this-pin there is journaled one end 254 (Fig-2) of an A-shaped driving member 256, the legs of which have at their ends bosses 255 (Fig. 5)' which are'journaled on a horizontal -shaft251 (Fig. 2), the latterbeing journaled in spaced vertical plates 258 which form a part of the frame of the machine. rThe shaft 251 extends through the forwardjside of one of the plates 258, as shown in Fig. l, and has fixed thereto anA arm 262, the free end of which carries a follower 264 arranged to bear Aagainst a traverse block 266 mounted on a worm or lead screw 304 (Fig. 2,) connected for rotation to the motor M3. Rotation of the lead screw 304 moves the traverse block 266 which in turn effects'movement of the arm 262 in a counterclockwise direction, thus turning the Afshaped driving member 256 in a counterclockwise direction to lift theelevator upwardly and forwardly. The proportions of the various operating parts are such that during the lifting movement the geometric lend a block 214.

center offfthe mold member moves along a line which isvertical and is parallel to the axis of the suspended'lamp. To assist in 'raisingthe elevator,` there is provided an air cylinder 268 (Figs. land 2) pivoted at .itslower lend 210 to a bracket 212 fastened to the frame of the machine and having at its upper venda piston rod 214 which is pivotallyvconnected at 216" to the A-shaped member 256 by way of a bracket 211.y Simultaneously with the movement of the -arm 2612 in a direction to produce upward movement of the elevator, air is admitted tothe cylinder 268( to impart anA upward thrust to the piston rcd21ll and hence to lift the elevator. In practice, su'icient airpressureis admitted kto the cylinderv to do abouttwo-thirds of the work necessary to raise thev elevator through the desireddistance, thus relieving the mechanical meansythat is themotor M3, from an undue load and permitting the use of a small motor. During the downward movement of the elevator, the. cylinder 268 acts as a dashpot to cushion the descent of the elevator which is Vquite heavy, there being an adjustable "bleederoriiice therein tov allow the air to escape slowly. Air is admitted A.

'to the cylinder on the upward stroke by a solenoid-controlled,valve VI, and is bled from the cylinder during descent through the adjustable orice. i

To produce rotation of thebending mold as if it ascends, thereby to roll the softened partially manufactured lamp about the mold, there is fastened to each shaft |18 a disk 268 over which passes a flat flexible band 210, one end' of which is fastened tol its periphery,v andthe other end .of which drops vertically downward through .a yguide slot 212 (Figi) in a -projection 213 formed o n-` the plate 258 and has on its lower When the mold members are in their lowermost position, the bands hang below the projections 213. As the mold rises, the bands slide through the slots 212 until the blocks 214 strike the lower side of the projections 213 whereuponthe shafts and hence the mold members begin to turn. adjusted on the bands so that rotation ofthe shafts will not begin. until the jawsg|1| have gripped the lower end of the lamp and also provides for adjusting the position at which rotation will begin to take place. To return the molds to vtheir original position-upon descent of vthe elevator, cables 216 are wrapped about grooved hubs1218 on the disks 268 and secured at one end thereto andat their opposite ends to one end of tensionsprings 280, theopposite ends of which arefastened to the frame of the machine. It is to be understood that other vmeans maybe provided for this purpose, for

example, a simple arrangement of gearing.

The jaws |1|, which grip the lower base vof 'YGO the lamp, comprise a pair of flat strips 286 (Fig. 3) set into the disks on a `radius thereof and having on their inner cooperating edges truncated notches 288.

To prevent the lamp froml cooling too rapidly as it is rolled up, the mold members are, while in their lowermost position, continuously heated by a gas jet or burner 290 (Fig. 2)situated therebelow and directed against the spaced mold members or by heating elements included in the mold members. Y

The location of the jaws |1| must be exact,

both at the beginning of the operation and at the end thereof, so that there will be no failure on the part of 4the 'jaws to grip the :lowerpend The blocks 214 may be on the base.

of thebaseand no oven-runat the. top which ywould stretch the:larnpgmorethan it should be.

Accordingly plates 29,4, carryingtwo bosses and .adjustable stop screws Y 296 and 298,. are fastened rigidly to the endsof eachof the shafts. |18. An arrnf-292 is pvoted to' :each plate- 294 and f ree to swing between the stop screws 296 and12 98. An anchor plate 300 surrounds the Yshaft |18 and-is fastened solidly to the boss |82. The anchorplate carries a pin 30| which projects youtwardly beyond thearm 292 at all times.) When the foregoing parts 291| .and' 292 'are at v the ,positions to V,begin the vbending operation, the

arm- 292 is forced against thepin 30| bythe plateZSe and stop screw 296. In thispos'iti'o'n thejaws. |1|l are horizontal. As the mold members rotate counterclockwise, as viewed. in Fig'.

i |during the ascent of the elevator, the arm 292 .travels completely around until it comes to rest against the` pin 38| .on the opposite side and .lwith the stop screw 2948 pushed againstit. This limits the rotation A of I Ythe mold Aat the upper -end of thee-,bending operation.

The lead screw 36.4l for traversing. the slide block 2,66`is driven bythemotorJM3. mounted This motor is driven first in one direction to- .raise the elevator and hence the moldmembers to the top, and then. in the reverse direction to bring the mold members down to their original position. 'Time' delay means Trl, to be described hereinafter, hc'lds4 the mold at the top temporarily to permit cooling of,v the rolled lamp. Preferably the lead screw iis ro:-

,tated slowly-until the-jaws grip" the lower end,

then rapidly to raise the elevatorto the tpwhere it ldwells and finally descentsv rapidly to its original position. As soon as the completed lamp is released by the vmold members and `they have hadtime todescend, the index headis stepped -around through one positionfand carries'thfe rolled-up lamp lthe next station' where it may beannealed and then transferred to a ma:- chine for exhaustingit or the present machine maybe provided at this station with a combined annealing oven and exhaustingapparatus. I

While the lamp is soft, land particularly during the rolling operation, there is a-tendenc'y for its walls tobecome somewhat flattened or distorted both .by the bending operation and by the tend- 'encyI for the rsoftened walls'to collapse. Accordingly, air or rare vgas under pressure is introduced to the interior of the'.lamp and" maintained therein from the moment the bendingfis :initiated until iti-is completed and thelamp. walls, have cooled. illustrated, each arm l'is provided withra .flexiblehose H (Fig. 11) having la'valve V3 (Fig. l2) 1 therein, one end o f the hose being `cennectedto- .a source of lair orra're gas pressure,

andthe other of which may bepres'sed overthe projecting end' of the exhaust tubeP- extending through the upper end of the-lamp vand providing communication with.. the interior. thereof. Means is alsoprovided-for .automaticallyI opening the valve V3 at the instant the mold begins to bend the lamp, and there is interposed between the valve and the connected endthereof an `ori nce of such size that the compressed airorVv gas is admitted under progressively increasing pressure throughout the rolling operation s o thatthe pressure increases with vthe stiffening of the lamp kand the increase inA bending thereof. The predetermined range necessary for securing `the desired results will vary with ythe kind of glass, vsize of the-tube and temperatureat kwhich-the 4tube is heated. At the conclusion oftherolling The powerfor effecting actuation of the parts 'of the machine is derived fromthe foregoing motors MI, M2 and M3, and a control circuit therefor will now be described with reference to Fig. 12. y

The motor MI for rotating the index head is energized from the terminals a and c of a conventional power source (not shown) by means of the normally open contacts .s 2| of a relay Mc operated by a solenoid Ll.v vThe solenoid LI lis energized from the power source terminals a and c by means of a momentary contact push button Aswitch 'smI which completes a circuit through 'the limit switches s1 and S8. The switch ss is operated by the hinge rod 92, being closed when the oven parts are open so rthat a lamp can be moved into the oven chamber by the index head I0. The switchsl is positioned on the end post 240 whereby thegcrosshead 236 closes the switch when the elevator is in the down position out of the path of the index head I0. Y

The energization of solenoid Ll, as above, conjointly closes the holding contacts S22 which are connected in parallel with the push button sml by the parallel limit switches S8 and s|0 thereby maintaining an energizing circuit for the solenoid L| after the push button sml is released. 'I'he switch s9 is opened b y a cam on the end of a camshaft C driven by the index head |0. 'I'he switch s| 0 is opened by an arm |8 as the preceding arm reaches the plasti'cizing and bending station. It will be evident that both of these switches'must be opened to drop out the relay Mc, thus stopping the motor AMI.

After the lamp is positioned in the bending position bythe index head I0, as described, the oven is closed byenergizing the motor M2 from the power source terminals a and c by means of a manually operated push'button switch sm2. This motor energizing circuit also includes a normallyV closed limit switch 'sl I operated by the oven hinge rod 92 and a normally open limit switch s|3 located upon the end post 240 and closed by the crosshead 236 when the elevator is in the down position. The energization of the motor M2 by means of the above circuit revolves the vdisk |22 through 180 degrees so that the links |26 and |28 rotate the hinge rod 92 to open the oven partsy 1D whereupon the limit switch sl I opens to deenergize the motor M2.

Y'I'he lamp stretches as it softens in the oven,

'thereby elongating until the lower end thereof trips thetrigger mechanism including a switch st thereby to complete a circuit energizing a solenoid L2 of a relay Er to close its normally open contacts s23 and conjointly open its normally closed contacts S24. K The rel-ay Er is preferably of the electronic type requiring only a change in the potential upon the control electrode of a vacuum ,tube to energize the solenoid L2 thereby to transfer its contacts.

. The closing of the contacts s24 energizes a time delay relay Tr3 from the power source terminals a. and c. After a time delay of approximately lfour seconds, the relay contacts S26 are closed by a solenoid L3, the relay time delay components, which are available as elements of a commercial relay, being omitted from the drawing for simplicity.

The delayed closing of the contacts s26 energizes a solenoid L4 of a relay Crl thereby tol open the normally closed contacts s2'| and concomitantly to close the'normally open contacts 528 andV 82.9- the contacts -being restrained in'the transferred positionby means of a detent which is shown schematically as the latch |20. vThe contacts 'S29 complete a circuit through the normally closed contacts S30 of a'second time relay Trl to energize the solenoid-operated valve V2 controlling the air supply to the air cylinder which closes the bending rolls.

The closing of' contacts '$21 completes a circuit paralleling the push button sm| to energize the ovenmotor M2 through a normally closed switch s|2 thereby revolving the disk an additional' 180 degrees to'its original position, thus opening the oven parts 10. rIl'heliinit switch s|2 is arranged so that it is opened by the oven hinge rod 92 when the oven is completely opened, thus deenerglzing the motor M2. The opening of the oven also closes another limit switch s6 to complete a cir- `cuit betweenthe terminals a and c which includes a solenoid-operated valve V| controlling the air supply to the elevator air cylinder 268, the contacts S28, the limitswitch s6 and the normally closed contacts 33| of a relay' Cr2.

Connected in parallel with the solenoid of the valve V| is a solenoid L6 of a relay Cr4 whereby the energization of the valve solenoid conjointly energizesl the solenoid L6 to transfer the normally 'cuit' which includes the relay contacts S38, the

normally closed interlocking contacts s42 of a relay Cr3, and the limit switches s| and s| being substituted for the conventional forward starting push button station of the speed control device. Thenormally closed limit switch sl is positioned on the post 242 so that it is contacted by the crosshead 236 when the elevator is in the uppermost limit of its travel thereby to stop the motor M3. The normally closed'limit switch s|`| acts as a safety interlock protecting the lead screw 304 being located at one end of the frame 260 so that the switch contacts are opened by the block 266 to stop the motor M3 before the block is jammed against the end of the frame. With the elevator in other than its uppermost position, the switches sl and s|`| are both closed so that the closing of the contacts S38 energizes the motor M3 to raise the elevator.

The heretofore described energization of the relay Er by the contact of the lamp against the trigger switch st opens the normally closed contacts s24 thereby interrupting a circuit energizing a solenoid Ll, with the result that the normally closed contacts S46 and s4'| controlled thereby connect a low speed rheostat RI t0 the speed control SC. The motor M3 therefor slowly moves the elevator upwardly until the lamp no longer closes the trigger switch st thereby interrupting the circuit energizing solenoid L2 thus closing the contacts s24 to again energize the solenoid Ll. The normally open contacts S46 and S41 close to connectl a high speed rheostat R2 to the speed control SC, thereby increasing the speed at which the motor M3 continues to raise the elevator for the actual bending operation.

At substantially the same time that the speed of the motor MS'is increased as described above,

the block266 closes a normally open limit switch sI8 located on thev frame 250. The switch SIB completes a circuit also including a normally closedlimit switch 'SI5 to energize a solenoid L8 of a relay Lr3. The solenoid L8 closes the contacts's48 to energize a solenoid valve V3 thereby supplying airor rare gas under pressure to the during the bending process. 'The'conjoint closing of the contacts S48 completes a holding circuit paralleling the switch sIBto maintain the solenoid L8 energized.: 1

When the bending operation is completed, the limit switch sI is opened by the block 266 to'stop the elevator motorM3. The block 266 simultaneously closes a limit switch sld to energize a solenoid'L9 of a relay Cr2 to transfer conjointly the contacts 83|, S32, S33 and S34. .The opening ofA the normally closed contacts s3I deenergizes solenoid L6- so that the contacts s38 and S39 return to their'normal positions stopping the motor M3. The solenoid valve VI is also deenergized by the contacts SSI but the air. cylinder continues. to support the load of the elevator because of the bleeder orice referred to heretofore. 1

Thenormallyopen'contacts S32 are closed to provide a parallel path forfenergizing the valve V2 controlling the air supply to the lamp gripping jaws upon the opening of the contacts S29 as described below. The contacts S33 close to energize the time delay relay Trl so that its solenoid LII opens the contacts S30 after the elapse vof approximately' 20 seconds, thereby providing time for the lamp to set in the bending rolls before the deenergization of the solenoid valve V2 opens the lower gripping jaws. The contacts S34 energize the solenoid LIZ thereby opening the latch |20 so that the contacts S21, S28 and S29 of the relay CrI returns to their normal position.

When the bending rolls reach their full open position, a rlimit switch s4 located on the block 2I0 is closed by the arm 266, thereby energizing solenoid LIS of the relay CTS to transfer the con-v tacts 34D, 34| and S42. The contact S40 completes va holding circuit for the solenoid LI3in parallel with the limit switch sri. The contacts S42 Aact as a safety interlock in the forward control' circuit. The contacts 84| close tocomplete the reverse control circuit for the speed/control CS which circuit also vincludes the normally closed limit switches s I 6 and s2. The switch s2 is located uponthe post 240 so that it is opened bythe crosshead 236 when lthe elevator isV in the down position. The limit switch sI6 is positioned on` ,s

the frame 260 near the left-hand end thereof, as is shown in Fig. l, so that it is contacted by the block 266 thereby protecting the lead screw from over-travel.

The completing of the reverse controll circuit bythe contacts SGI, as described above, reverses the motor M3 so that the elevator is lowered toward its down position. During the descent the crosshead 236 contacts the limit switch SI5 which is located on the frame member 244 thereby to deenergize the solenoid L8 of the relay LTB, thus opening the valve V3 supplying air or 'rare gas to the interior of the lamp. As the elevator reaches the bottom of its downward travel, the limit switches s2, s3, s'I and si3` operate. As described above, the opening of s2 :stops the elevator motor M3. The opening of the .limit switch s3 deenergizes `the solenoid LIS of the relay GT3 thus returning the contactsl S40', s4| and s42 to `their normal-positions. Switch s1 closes sothat interior of thel lamp so that it does .not collapse 'smI..

Torecapitulate very generally, partially manufacturedlamps are loaded on the indexhead by Aengagement of the upper clamp vcap BI between the jaws 28a-28h, the oven I2 is heated by turn.- ing on the current to its heating coils, the .preheating oven I2 is likewise energized, .if preheating is employed, and thecompressedfair or -gas conductors are connected to a suitable source of 'compressed airY or gas both; to supply air.` Vto the'llamp during heating and'to the cylinders 2,I4 and 2 68 which, respectively, close-the mold members and assist in raising the elevator E. At this point the machine is ready to start andthe first step in the cycle of operation is effected by the push button' switch vsmI just described which steps the index head one-eighth of a turn to bring Athe first lamp into the oven I2. The oven is then closed by the push buttonrsm2. It isto be understood that the machine could be completely automatic so that it would perform itsentire 'seriesof yoperations merelyv byfactuating the switch smi'. Asillustrated hereinafter, however, it is not until thepush button cm2 `is closed that the: operation becomes automatic and is completelyunderthe control of the latch or triggersWitChStWhiCh;las heretofore described, is ldepressed by elongation of the lamp upon heating. Depression'of: the trigger switch st starts the oven motor M2 to open the oven and starts the elevatorlmotor M3 which rotates the traversing screw, hence raising the elevator and hence the molds towardthe lower end -of the lamp. As the jaws come oppozsite the lower end, the piston cylinderassembly 254 is actuated tcclose'V them on thelower clamp cap, the slack in the strip 210 is taken up, and the molds begin to rotate as the .elevator continues to rise. At the upper extremity of its movement the moldmembers dwell for a suillcient length of time, governed by a" time delay switch; to permit the lamp to set, whereupon the airto piston cylinder assembly 2I`4 is cut off, the ,jaws are vseparated by the tension Ispring 2II to reieaseithe @neef the'i'amp, the motor M3 is r2.-

ve'rsed, `and the mold members are returned to 4:therein for this purpose. As soon Vasrthe mold .members comete rest in their initial position,

means is actuated to vstep the index head around one position, that ische-.eighth of a turn, so that the vcompleted lamp is moved to thenex'tv station in the circuit, marked A, and another lamp is introduced to the oven I 2. At the station 1A, the post 38 is either manually or automatically tilted tov an inclined position to bringthe exhaust tube P to arnearly vertical positionthereby to facilitate'exhausting the lamp andpreparing itkfor exhausting and tipping. The lamp'maythenbe annealed at the same station or at asucceeding station constituting an annealing oven rAint o which it may be passed As shown, thestation A( is acontinuous extension ofthe station" A, however it .may be independent thereof.`

It should be understood thatthe presentdisclosure is for the purpose of illustrationonly and that this invention includes all modifications and equivalents which fall within the scopev of kth appended claims.` We claim: a 1. A machine for converting a'partially manufacturedstraight lamp tube into asubstantially circular lamp comprising supporting means for suspending the lamp from one end means for softening the lamp sufliciently so that elongation takes-place due to its suspended weight, circular mold means engageable with the opposite end of the lamp, power operated means for effecting engagement of the mold means with said opposite end of the lamp and movement thereof in directions to wrap the lamp thereabout, a motor for supplying the power necessary to effecthoperation of said power operated means, means situated in a position toA be contacted byV elongation of the lamp and operable by a predetermined elongation of the lamp to initiate operation of said motor.

2. A machine for converting a partially manufactured straight lamp tube having clamp caps at its opposite ends into a substantially circular lamp wherein the ends are adjacent, comprising means for suspending the lamp from one end means for softening the lamp suiliciently so that lelongation takes place due toits suspended weight, circular mold means situated at the opposite end of the lamp, clamping jaws carried by the mold means, power operated means for eifecting operation of the mold means to engage the jaws with said opposite end of the lamp and to impart to the mold movement to wrap the lamp thereabout a motor for supplying the power necessary to effect operation of the power operated means, anda trigger means at said opposite end of the lamp movable by contact of said opposite end of the lamp therewith upon reaching a predetermined length to initiate operation oi said motor.

' 3. A machine for converting a partially manufactured straight lamp tube into a substantially circular lamp wherein the ends are adjacent, comprising means for suspending the lamp from one end means for softening the lamp sufliciently so that elongation takes place due to its suspended weight, a mold member for engaging the opposite end of the lamp, power operated means foreffecting movement of the mold in directions to wrap the lamp thereabout, a motor for supplying the power necessary to effect operation of said power operated means, a centering device situated at said opposite end of the lamp for engagement with its lower end, said centering device being in vertical registration with the lamp supporting means so as to maintain the lamp .perfectly straight, said centering device being movable by contact of the lamp therewith through elongation of the latter as it softens to initiate operation of said motor.

` 4. vA machine for converting a partially manufactured straight lamp tube having clamp caps at its opposite ends into a substantially circular lamp wherein the ends are adjacent, comprising means for suspending the lamp from its upper end when in a softened state so that its longitudinal axis is substantially vertical, circular mold means engageable with the clamp cap at the lower end of the lamp, said mold means being movable in translation and rotation, means for effecting translational movement of the mold means parallel to the longitudinal axis of the lamp, said means including a beam on one end 'of whichthe mold means is pivotally mounted, a cross head movable horizontally to and from the axis of the suspended lamp to which the other end of the beam is pivotally fastened, a lever movable angularly about a predetermined center, one end of said lever being pivotally fastened to the beam substantially midway between its ends, means for effecting angular movement of the lever anda flexible element having one end wrapped around the mold means and its other end xed so that elevation of the beam simultaneously rotates the mold in a direction to bend the softened lamp around the mold.

5. A machine for converting a partially manufactured straight lamp tube having clamp caps at its opposite ends into a curved lamp, comprising means for suspending the lamp from its upper end while in a softened state so that its longitudinal axis is substantially vertical, mold means engageable with the clamp cap at the lower end of the lamp, means for guidingv the mold means in a path parallel to the longitudinal axis of the lamp, said means including a beam on one end of which the mold means is pivotally mounted, a cross head, horizontal tracks supporting the cross head for movement to and from the axis of the suspended lamp, to which the other end of the beam is pivotally fastened, an elevating lever movable angularly about a predetermined center, one end of said lever being pivotally fastened to .the beam substantially midway between its ends, angular movement of the elevating lever being operable. to slide said other end of the beam rearwardly along the track and simultaneously rotate the beam in a counterclockwise direction about said other end, depressl its one end and operable to slide said other end forwardly along the track and simultaneously rotate the beam in a clockwise direction about said other end to elevate said one end, means for eifecting rotation of said lever and means for cushioning the movement of the beam in its counterclockwise movement. i

6. A machine for converting a partially manufactured straight lamp tube having clamp caps at its opposite ends into a curved lamp, compris'- ing support means for suspending the lamp from its upper end while in a softened state so that its longitudinal axis' is substantially vertical, a mold means having clamps engageable with the clamp cap at the lower end of the lamp, means for guiding the mold means in a path parallel to the longitudinal axis of the lamp, said means including a beam on one end of which the mold means is pivotally mounted, means supporting the opposite end of the beam for pivotal movement and linear movement to and from the suspended lamp, an elevating lever pivoted for angular movement about its xed center, one end of said elevating lever being pivotally connected to the beam substantially midway between its ends, a reversible motor for effecting angular movement of the elevating lever to raise and lower the beam, a piston and cylinder assembly, said piston having a rod connected to the beam, means for effecting operation of the motor in one direction to rock the elevating lever in a direction to raise the beam and in the other direction to lower the beam, means operable simultaneously with the operation of the motor to effect raising of the beam to admit a uid pressure to the cylinder, to move the piston in a direction to assist in raising the beam, means to cut off the fluid pres- Sure t0 the Cylinder as the motor reverses its direction of rotation to lower the beam and a bleeder valve in the cylinder to permit the fluid pressure to leak out slowly.

7. A machine for converting partially manufactured straight lamp tubes into curved lamps, comprising an index head, radially extending arms on said head, a clamp near the end of each arm-,adapted to.- receiveanend of `a lamp to holdit` suspended with itslongitudinal axis substantially vvertic'alva two-part oven, the parts ofYV movable vertically parallel tothe axis-loi thev lamp and being rotatable about a horizontal axis at right Vangles to the longitudinal axis of the lampfclamp means on the mold means normally open` when -the oven-fis closed,V a trigger directly below .the lower end of the-oven in a position to bedepressed by the lamp upon elongation thereoff-'due to softening,- poweroperated means operable tof-openthe oven raise the mold from belowtheoven to the-level of the lower end of the lamp, close the clamps on the lower end, effect vertical and rotary movement of the mold to wrap the soft lamp about the mold, disengage the clamps from the lower end of the lamp when it is completely formed and eifect movement of the completed lamp away from the oven while moving the next lamp on the index head into the oven a motor for effecting operation of the power operated means, operation of said motor being initiated by depression of the trigger, a motor circuit and means in the motor circuit for driving the motor at a low speed until the clamps reach the level of the lower end of the lamp and clamp it and for thereafter driving it at a high speed to wrap the lamp into the annular groove.

8. In an apparatus for bending glass tubes, an index head for holding the tubes suspended from one end, a heating unit for plasticizing the tubes preliminarily to bending, said index head being movable successively to bring tubes to the place of the heating unit, means for initially eiecting movement of the index head to step it through a distance corresponding to the spacing of the tubes thereon to bring a tube to said place oi heating, and other means operable by a predetermined elongation of the tube due to softening to continue rotation of the index head at intervals depending upon the time required to effect softening of the tubes in the heating unit.

9. In an apparatus for bending glass tubes, an index head for holding the tubes suspended from one end, a heating unit for plasticizing the tubes preliminarily to bending, said index head being movable successively to bring the tubes to the place of the heating unit, means for eiiecting movement of the index head initially to step the head a distance corresponding to the spacing of the tubes thereon to bring a tube to said place of heating, and other means operable by a predetermined elongation of the tube in the heating unit to continue rotation of the index head at intervals controlled by the time required to effect heating of the tube to said elongation, said other means being inoperative to eiiect rotation of the index head in the absence of a tube in the heating unit.

l0. A method of bending glass tubing comprising heating the tube to soften its walls, cooling one side without spoiling its plasticity and then bending the tube so that the softer side forms the inside of the bend.

1l. A method of bending a glass tube comprising the steps of heating the tube to soften its walls,.,cooling a portion of its walls at one side more than the other while maintainingv the'en-f. tire wall plastic, and then bending the tube into,

substantially circular form and in a directionso e thatthesofter side forms the inside ofthe article so. formed.:

v12..A Amethod forv bending a glassv tube com-r prisingthe steps of subjecting the t-ubeto atem-f.

perature suiiicient to plasticizeit asa whole, cool-.g

ingal portion of its; walls to make it less plastic along one side, and then bending the tube into,v

substantially circular shape in such ardirection that the side of lower` plasticity is onthe insidev of the bend.

13. A method Ofbending a comprises. the stepsof differentially plasticizing the4 tube. to.v soften one side vmore than the other;- and then bending the tube so, that the softer side.

ison the inside of the bend.

' 14. A method .of vvbending' a glass plasticize. it, cooling one side .withoutreducing',itsv plasticity to a point where it can not be bent, quickly wrapping the tube around a heated mold with the uncooled side in contact therewith to form an annulus and progressively increasing the pressure within the tube during the wrapping of the tube about the mold.

15. A method of bending a glass tube comprising the steps of suspending the tube from one end, heating the tube to plasticize its walls, playing a current of air on one side of the tube to make that side somewhat less plastic, and then bending the tube by moving its free end in such a direction that the less plastic side is on the inside of the bend.

16. A method of bending a glass tube comprising the steps of supporting and plasticizing the tube, playing a current of cooling media on one side of the tube to make it less plastic on that side, and then wrapping the plasticized tube about a circular mold member with the side of greater plasticity in contact with the curved surface of the mold.

17. A method of bending a glass tube comprising the steps of supporting and plasticizing the tube, playing a current of air on one side of the tube to make it less plastic on that side, and then wrapping the plasticized tube about a heated circular mold member with the side of greater plasticity in contact with the heated circular surface of the mold member.

18. A method of bending a glass tube comprising the steps of supporting and plasticizing the tube for bending it about a circular mold member and then playing a current of cooling media on the wall of the tube which will be exposed when it is wrapped about said mold and throughout the length thereof which shall extend around substantially the lower half of the mold member.

19, A machine for converting a partially manufactured straight lamp tube having clamp caps at its opposite ends into a curved lamp tube comprising supporting means for suspending the lamp from its upper end while in a softened state n means having two parts mounted on the elevator glass `tube which..

tube which; comprises the. steps of heating the entire tube to:

19 for rotation about a horizontal axis and movable to andfrom each other, levers on the elevator connecting the mold parts and movable to bring the mold parts together, means for effecting vertical movement of the elevator from its lowermost position to the level of the lower end of the lamp, and from the lower end of the lamp to near the top of the lamp and back again to its lowermost position, cam bars holding the parts positively separated during the initial movement of the elevator from its lowermost position to the level of the bottom of the lamp, said cam bars terminating at said level, a uid operated piston operably connected to the levers on the elevator for positively closing the mold parts, operation of said iluid operated piston being initiated as the elevator rises toward the lower end of the lamp, but being rendered ineffective until the cam bars are cleared, whereupon the mold parts close on the lower end of the lamp, means near the upper limit of movement of the elevator to render the fluid operated piston ineffective, and

20 yieldable means connected to the levers for separating the mold parts when the' iluidv operated piston is rendered ineiective to release the base of the lamp and to hold the mold parts separated until the elevator returns to its initial position.

HOWARD C. SNOW.

EVERE'I'I F. KELLEY.

SAMUEL S. SAYWARD.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS I 

